A multiplier is applied to each SMS message based on the destination country, which could explain why NTO is already at 75% utilization for their annual Super Messages. For example, sending an SMS message to a subscriber in Germany consumes 1.5 Super Messages, while sending an SMS message to a subscriber in India consumes 3 Super Messages. The other options are not true or relevant.

To achieve faster send speeds for large volumes of emails, the functionality known as Burst Sending should be utilized. Burst Sending allows Marketing Cloud to process and send large batches of emails quickly, meeting high send speed goals by maximizing the throughput of the sending infrastructure.
Reference: Salesforce Help - Burst Sending

Publication lists in the Marketing Cloud are used to allow subscribers to opt-down or opt-out of specific types of communications without unsubscribing from all communications. This functionality enables more granular control over communication preferences, helping organizations maintain engagement with subscribers who might not be interested in all content but still wish to receive certain types of messages.
Reference: Salesforce Help - Publication Lists

Creating separate business units for each brand is necessary when:
Brand-specific Domains: Separate business units allow for the configuration of brand-specific private domains, which are crucial for maintaining brand identity and trust in email campaigns by customizing link and image paths.
Use Case: If different brands under NTO need to leverage their unique domains for sending emails and hosting content, setting up distinct business units allows each brand to manage its sender profiles, content, and subscriber interactions independently.
Reference: Salesforce Marketing Cloud Business Units

The Export Email Allowlist feature allows the admin to specify a list of email addresses that are authorized to receive data exports from Marketing Cloud. This feature can help protect against misuse of customer data by preventing unauthorized users from exporting data without approval. The other features do not directly address the requirement of restricting data exports.